1. Field of the Invention
The present invention relates to a foil-line closure lid for a container with a slit molded into the closure skirt to receive folded tabs of a foil liner.
2. Description of the Prior Art
There are many composite paper and aluminum foil containers on grocery shelves and in snack-shops or other marketing areas today that utilize a foil membrane to seal at least one end of a package or container. These containers, cans or packages have a rolled bead surrounding the mouth, the foil membrane being adhesively attached to the top of the bead. A plastic closure is usually provided to protect the foil membrane and to provide re-sealing means.
In some situations, the foil membrane is sealed directly to the top of the can or container, and the plastic closure or lid is applied in a second operation. The sealing is accomplished by activating a hot melt coating on the foil with heat inducing means, either via convection or induction. In other situations, the foil is inserted into the plastic closure or lid. The closure or lid is then applied to a rolled bead can or container and the assembly is passed under an induction coil to heat the metal foil and activate the hot melt coating to accomplish the seal in one step.
Although the last method described is desirable in several aspects thereof, there must be noted that inherent problems are encountered as follows:
(1) It is difficult to retain the thin foil membrane in a plastic closure during packing and shipping of the closures, and in application to the can or container;
(2) For package or container opening purposes, it is desireable that the foil membrane include a tab or projection that can be grasped with fingers so that the sealed membrane can be peeled from the mouth of the container neatly.
In a situation where the foil is applied prior to the plastic re-closure, it is possible to either form the tab downwardly along the container sidewall after the seal is accomplished, or to fold it back so that it lies underneath the closure panel. However, if it is desired to insert the foil into a closure prior to application thereof with respect to a container, it is necessary to fold the tab over prior to inserting the foil membrane into the closure so that the tab does not interfere with subsequent closure packaging and application operations. This creates a double thickness of foil, and problems can be encountered when trying to effect a heat seal to the rolled bead of a container; pressure must be applied to force the foil membrane to conform to the container bead, but it is difficult to generate enough pressure to guarantee a perfect seal at the points adjacent either side of the folded tab.
In the prior art there exists a U.S. Pat. No. 3,892,351--Johnson et al dated July 1, 1975 which discloses a closure with a multitude of finely pitched, radially spaced ribs in a top panel of the closure directly above the seal area. These ribs were intended to force a foil membrane to conform reliably to the container bead along points on either side of a folded tab. Also there exists a U.S. Pat. No. 3,973,719--Johnson et al dated Aug. 10, 1976 which is a division of the foregoing U.S. Pat. No. 3,892,351--Johnson et al and which relates to a container assembly and method involving induction heat sealing of a membrane-type closure. Still another division of the foregoing U.S. Pat. No. 3,892,351 is represented by U.S. Pat. No. 3,988,185--Johnson et al dated Oct. 26, 1976 which also relates to a container assembly and method employing induction heat sealing. Similarly, a U.S. Pat. No. 4,139,643--Hix et al dated Feb. 13, 1979 and a U.S. Pat. No. 4,164,588--Johnson dated Aug. 14, 1979 exist disclosing a snack food package and a package liner and fragile snack chip combination respectively related to a package liner of a type with which a foil-lid combination for containers according to the present disclosure can be utilized.